Dandelion vortexes

Surprisingly, dandelion seeds use a method of flight previously thought impossible.

Abstract
Wind-dispersed plants have evolved ingenious ways to lift their seeds1,2. The common dandelion uses a bundle of drag-enhancing bristles (the pappus) that helps to keep their seeds aloft. This passive flight mechanism is highly effective, enabling seed dispersal over formidable distances3,4; however, the physics underpinning pappus-mediated flight remains unresolved. Here we visualized the flow around dandelion seeds, uncovering an extraordinary type of vortex. This vortex is a ring of recirculating fluid, which is detached owing to the flow passing through the pappus. We hypothesized that the circular disk-like geometry and the porosity of the pappus are the key design features that enable the formation of the separated vortex ring. The porosity gradient was surveyed using microfabricated disks, and a disk with a similar porosity was found to be able to recapitulate the flow behaviour of the pappus. The porosity of the dandelion pappus appears to be tuned precisely to stabilize the vortex, while maximizing aerodynamic loading and minimizing material requirements. The discovery of the separated vortex ring provides evidence of the existence of a new class of fluid behaviour around fluid-immersed bodies that may underlie locomotion, weight reduction and particle retention in biological and manmade structures.

Dandelion seeds fly using ‘impossible’ method never before seen in nature
Nature, Revealed: the extraordinary flight of the dandelion
Paper, A separated vortex ring underlies the flight of the dandelion
Research Gate project, The form and function of the dandelion fruit

Dandelion pollen
2018 PhotoMicrography Competition
Dandelion fiber
2018 PhotoMicrography Competition

Royal Society of Open Science publishes Terraforming the Biosphere

Ecosystems are complex systems, currently experiencing
several threats associated with global warming, intensive
exploitation and human-driven habitat degradation. Because
of a general presence of multiple stable states, including
states involving population extinction, and due to the intrinsic
nonlinearities associated with feedback loops, collapse in
ecosystems could occur in a catastrophic manner. It has been
recently suggested that a potential path to prevent or modify
the outcome of these transitions would involve designing
synthetic organisms and synthetic ecological interactions that
could push these endangered systems out of the critical
boundaries. In this paper, we investigate the dynamics of the
simplest mathematical models associated with four classes
of ecological engineering designs, named Terraformation motifs
(TMs). These TMs put in a nutshell different ecological
strategies. In this context, some fundamental types of
bifurcations pervade the systems’ dynamics. Mutualistic
interactions can enhance persistence of the systems by means
of saddle-node bifurcations. The models without cooperative
interactions show that ecosystems achieve restoration through
transcritical bifurcations. Thus, our analysis of the models
allows us to define the stability conditions and parameter
domains where these TMs must work.

download the paper

If everyone does a little bit, great things can happen

Sap-sucking bugs manipulate their host plants’ metabolism for their own benefit

Stink bug

Free-living insects are able to move between and feed from different plants in the wild, unlike their less mobile endophytic counterparts, which spend a large part of their lives in a restricted area of the plant, often inside the tissues. When plants are targeted by bugs that depend on them for food and shelter, they often rely on defence responses that deter their attackers. However, some insects manipulate these mechanisms to counter the plants’ defence and even create a better nutritional environment around feeding sites. Until now, it was believed that only endophytic insects employed this strategy. … more

Cytokinin transfer by a free-living mirid to Nicotiana attenuata recapitulates a strategy of endophytic insects

Species, Variety, Cultivar

Groups

  • Angiosperms: Flowering plants
  • Gymnosperms: Conifers, cycads, allies
  • Pteridophytes: Ferns
  • Bryophytes: Mosses and liverworts
  • Families:

  • Currently 642 families
  • Genus:

  • Currently 17,020
  • Group of related plants
  • Origin, type, group
  • Species:

  • Genus name + specific feature that makes it different than other plants in Genus
  • Breeds true from seeds or cloning
  • The largest group in which two parents can create fertile offspring
  • Variety:

  • Usually occurs in nature and have same characteristics of parents
  • Seeds from varieties usually have same characteristics
  • Always written in lower case
  • Hybrid:

  • Crosses between species or different parentage in the species
  • Seeds rarely breed true
  • Cultivar:

  • Cultivated variety, created by humans. Some are mutations, some are hybrids of two plants.
  • Seeds don’t usually breed true, propagation by cloning is needed ( from cuttings, tissue culture )
  • First letter of a cultivar is capitalized
  • Heirloom:

  • Varieties found in nature for at least 50 years
  • The Plant List on going list of all known plant species

    Seeds: Species, F1, F2, F3

    P1 Species seeds are from two parents of the same species or self pollination
    — breed true

    F1 seeds are hybrids created from two unrelated parents ( children )
    — hardy crosses, usually vigorous, healthy plants, children usually look like the children

    F2 are self pollinated F1s or pollinated by other F1s ( grandchildren )
    — might look like parent, might look like mailman, most diverse, greatest diversity in this cross

    F3 are self pollinated F2s or by other F2s ( great grandchildren )
    — who knows? usually selected to strengthen an F1 trait

    F4, F5, F6 can also be found

    The ‘F’ is short for filia

    Species seeds are the most expensive, each F? gets cheaper the farther you travel down the family tree

    S seeds are self fertilized seeds that have been treated chemically, or otherwise, to create a mutation. It’s not an accepted botanical grading, but often used by hobbyists

    Crowdfunded fern genomes published in Nature Plants

    Photo: Laura Dijkhuizen

    On July 17, 2014, the world decided it wanted to learn the genomic secrets hidden in the beautiful little, floating water fern, Azolla filiculoides. Not only did they want to know, but they paid for it too – a whopping $22,160 from 123 backers – through a crowdfunding site called Experiment.com (Azolla, a little fern with massive green potential).

    Four years later, they have what they paid for, and more! The project was backed at 147% of the budgeted goal, which allowed the researchers to sequence and analyze the first fern genome ever. With the extra funds, they could sequence a second fern, Salvinia cucullata. Their results appear this month in the journal Nature Plants (Fern genomes elucidate land plant evolution and cyanobacterial symbioses).. . . . (read more Fern-tastic!

    An orchid matches its scent rhythm to the locals

    Interesting, white flowers are white to attract pollinators at night, several orchids I’ve owned have a scent that is very strong after dark but barely there during the day.

    We find that the floral scent of the orchid Gymnadenia conopsea differs between day and night, and the increase in scent from day to night is stronger in populations with nocturnal pollination. This is the first study to report genetic variation in floral scent emission rhythms within the same species, and this is an important first step to understand the evolution of floral scent.

    read more…

    Diel pattern of floral scent emission matches the relative importance of diurnal and nocturnal pollinators in populations of Gymnadenia conopsea